Ribosome and RNA Structure and Function: At the present time, more needs to be learned about ribosome structure such as particle surface structure, amount and nature of RNA exposed, and RNA functions to fully understand the mechanism and regulation of protein synthesis. The aim of the proposed work is to gain information on the structure and function of Escherichia coli ribosomes, in particular, the nature of the exposed RNA on the surface of the ribosomes and the role of the RNA in protein synthesis. One approach to ribosome structure that this laboratory is currently using is the modification of the intact particles, either with enzymes or by chemical means and the identification of the altered components. Information on binding sites of aminoacyl t-RNAs, supernatant factors and antibiotics is also being sought. In addition, the functional capacity in protein synthesis of ribosomes having modified RNA regions is being studied. This should yield information on the functional capacity (or lack) of the specific RNA regions in various aspects of protein synthesis.